Automatic color electrophotographic apparatus



Sept. 16, 1969 s. w. JOHNSON 3,457,468

AUTOMATIC COLOR ELECTROPHOTOGRAPHIC APPARATUS Filed March 30, 1967 7 Sheets-Sheet l "IN I 4, m6, 5

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United States Patent US. Cl. 355-4 -20 Claims ABSTRACT OF THE DISCLOSURE Automatic apparatus for making a colored electrophotographic print of an original colored image has a platen for positioning a recording medium at a predetermined distance from a light-image projector during its entire processing. Different light images of the original colored image are projected automatically, at appropriate times, in registration onto a photoconductive surface of the recording medium. A processing head which is re ciprocated automatically over, and slightly spaced from, the photoconductive surface is controlled to charge the photoconductive surface electrostatically, to tone electrostatic images formed on the photoconductive surface With selected toners, and to rinse each of the toned images.

BACKGROUND OF THE INVENTION This inventio relates generally to automatic electrophotographic apparatus, and more particularly to improved apparatus for making a colored electrophotographic print from a colored original image. The improved automatic electrophotographic apparatus is particularly useful for making a colored electrophotographic print from a colored photographic transparency, such as a 35 mm. colored photographic slide or the like.

It has been proposed to make a colored electrophotographic print from a colored original image by first making a plurality of different photographic colored separation transparencies from the colored original image and then superimposing toned latent electrostatic images produced by each of the separation transparencies on a charged recording medium. In some prior-art apparatus, especially where it is necessary to move the recording medium during its processing, the operations of superimposing different toned images over each other in good registration present a difiicult problem. Most of the priorart toned images, especially when wet, are layers of toners which are usually too thick to take a good electrostatic charge for the formation of subsequent superimposed toned images, and the resulting superimposed toned images, of different colors do not blend well with each other, when dry, to produce the desired natural colors of the original image. Also, many prior-art apparatus for making colored electrophotographic prints are relatively complex and expensive because they require a multiplicity of sets of processing means, including image projecting means, charging means, and developing means for each color used. Such apparatus also require involved conveying means and image registration means for transporting the recording medium from one set of processing means to another and for superimposing toned images of different colors over each other in good registration on the recording medium.

It is an object of the present invention to provide improved automatic electrophotographic apparatus for making a colored electrophotographic print that overcomes the aforementioned disadvantages of the prior-art apparatus.

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SUMMARY OF THE INVENTION Briefly stated, the improved automatic apparatus for making a colored electrophotographic print comprises means for positioning a recording medium in a predetermined relation with means for projecting a light image onto the recording mediums photoconductive surface, and a processing head which is adapted to be reciprocated adjacent to the recording medium by processing control means.

In a preferred embodiment of the improved automatic apparatus, the photoconductive surface of the recording medium is both rinsed and charged before the first electrostatic latent image is formed on the photoconductive surface. In one direction of movement across the recording medium, the head is adapted to tone any electro static image formed on the photoconductive surface with a selected toner. In an opposite direction of movement, the head is adapted to rinse the toned image and to charge the photoconductive surface prior to the formation of a subsequent latent electrostatic image to be produced thereon. The rinse liquid is preferably very volatile and evaporates almost instantaneously when applied as a. rinse on the toned electrostatic image. The rinse liquid functions to clean the photoconductive surface initially, to provide an improved surface for taking a good electrostatic charge, to remove excess toner from the toned image, to substantially fix each toned image, and to provide thin layers of toner in each toned image so that the colors of the superimposed toned images that form the composite finished colored electrostatic print blend together to provide the substantially true colors of the colored original image.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view, viewed from the top and front, of one embodiment of the improved automatic electrophotographic apparatus, illustrated with some parts broken away to expose internal parts;

FIG. 2 is a perspective view, viewed from the back, of the improved apparatus shown in FIG. 1;

FIG. 3 is a cross-sectional view of a portion of the improved apparatus taken along the line 3-3 in FIG. 1;

FIG. 4 is an enlarged front elevational view of a portion of the improved apparatus shown in FIG. 1, showing the recording medium drive means and the processing head drive means;

FIG. 5 is an enlarged fragmentary perspective view of the filter drive mechanism and exposure control means shown in FIG. 1;

FIG. 6 is an enlarged perspective view, viewed from the top and side, of the improved processing head shown in FIG. 1;

FIG. 7 is a perspective view, viewed from the bottom and side, of the improved processing head shown in FIG. 6, one part being broken away;

FIG. 8 is a fragmentary cross-sectional view of the improved apparatus taken along the line 88 in FIG. 4;

FIG. 9 is a fragmentary cross-sectional view of the improved apparatus taken along the line 9-9 in FIG. 8;

FIG. 10 is a perspective view, viewed from the top and side, of another embodiment of a processing head suitable for usewith the improved apparatus shown in FIG. 1;

FIG. 11 is a perspective view, viewed from the bottom and side, of the processing head shown in FIG. 10;

FIG. 12 is a timing diagram listing the sequential functions of the automatic electrophotographic apparatus shown in FIG. 1, and showing the duration of these functions by a graphic representation in arbitrary units of time; and

FIG. 13 is a schematic wiring diagram of the control circuit of the improved automatic electrophotographic apparatus shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT General.Referring to the drawings, particularly to FIGS. 1 and 2, there is shown improved apparatus for making a color electrophotographic print automatically from a colored transparency. The apparatus 10 has a control circuit (FIG. 13) for operating its components to provide all of the functions of a colored electrophotographic process automatically. The electrophotographic process includes the operations of electrostatically charging an electrically insulating photoconductive surface -11 of a recording medium 12, exposing the charged surface 11 with a projected light image of a colored transparency through a selected colored filter to produce a latent electrostatic image, toning the latent electrostatic image with a selected colored toner, and rinsing the toned image to substantially dry it. The control circuit sequences and times each operate automatically. The finished colored electrophotographic print comprises a plurality of toned images superimposed on each other, in registration, in a. manner to be hereinafter explained in detail.

The apparatus 10 is contained in a cabinet 13, having an upper compartment 14 that is preferably enclosed with panels or doors (not shown) to make it light proof. A lower shelf 15 of the cabinet 13 is used to support heavy components of the apparatus 10. The cabinet 13 is supported on a plurality of casters 16 to render it portable.

The light-image projection system.-The original colored image to be copied, such as a 35 mm. Kodachrome photographic transparency 17 (FIG. 3) is inserted within a slide holder 18 of a projector 20, such as a photographic enlarger, to project light images of the transparency 17 onto the surface 11 of the recording medium 12 through selected (light absorption media) color filters 28, 29, 30, 32, and 34 disposed in a filter wheel 36. The slide holder 18 is a disc-like member, rotatable about its center, and provided with oppositely disposed notches 21 and 22 that cooperate with a detent spring 23 for positioning the transparency 17 either inside or outside the projector 20. A peripheral cam 24 on the slide holder 18 is adapted to momentarily close a normally-open starting switch 26 when the slide holder 18 is rotated to position the transparency 17 within the projector 20. The sequencing of each light image, the selection of the proper filter and the duration of each exposure are controlled by the control circuit (FIG. 13) hereinafter explained in detail.

As shown in FIG. 5, the filter wheel 36 is adapted to be rotated about its center by a filter motor M3 and friction drive means 37 coupled between the periphery 38 of the filter wheel 36 and the motor M3. An appropriate filter in the filter wheel 36 is disposed between a projection lens 39 of the projector and the photoconductive surface 11 of the recording medium 12 by the control circuit (FIG. 13), most of which is disposed within a compartment 42 (FIG. 2) attached to a rear wall 44 of the cabinet 13.

The filter wheel 36 is positioned accurately for each exposure by means of a detent solenoid 46. When actuated, the detent solenoid raises a spring-biased pin 48 which is adapted to rest in one of a plurality of dimples 50 disposed adjacent to the periphery of the filter wheel 36. An exposure lamp (20a, FIG. 13) within the projector 20 (FIG. 1) for projecting the light images is controlled by the control circuit through one of a plurality of timers T2T5 and T7 in a manner to be hereinafter explained. The timers T2T5 are fixed to the back of the rear wall 44 to render them accessible for easy adjustment, and the timer T7 is fixed to the rear wall 44 within the compartment 14.

The diaphragm setting (lens opening) of the projector 20 (enlarger) is set for each original color transparency by means of commercially available exposure control apparatus 52 (FIG. 1) that includes the timer T7 and a motor 54, as shown in FIGS. 1 and 5. A shaft 56 of the motor 54, is coupled to the diaphragm control means of the enlarger 20 by any suitable means, as by worm gear drive means (not shown), in a manner well known in the photographic art. A photoelectric cell 60 (FIG. 1) is disposed in a metal platen 62 supported on a rigid bed 65. The cell 60 senses the light transmitted through the transparency 17 in the projector 20 and provides the exposure control apparatus 52 with a signal which, in turn, controls the rotation of the motor 54 to adjust the lens opening of the projector 20* to a suitable diaphragm setting.

The record medium transport systems (FIGS. 1 and 4).The recording medium 12 comprises a backing of relatively electrically conductive material, such as paper, having a coating of photoconductive material, such as Zinc oxide in a resin binder, on one surface thereof to provide the photoconductive surface 11. The photoconductive surface 11 should be dye sensitized, in a manner known in the art, to render it responsive to all colors in the visible spectrum. A roll 64 of a web of the recording medium 12 is supported on a shaft 66 which, in turn, may be coupled to a suitable clutch (not shown) to regulate the unreeling of the roll 64. The recording medium 12, from the roll 64, is passed under an idle roller 68, over the platen 62, and between a pair of rollers 70 and 72. The roller 72 may be of rubber and forms drive means with the roller 70 to pull the recording medium 12 from the roll 64. The roller 70 is fixed to a pulley 73 which, in turn, is coupled to a pulley 74 through a drive belt 76. The pulley 74 is coupled to a paper drive motor 78 through a reduction gear box 80. The paper backing of the recording medium 12 is disposed against the upper surface 63 of the platen 62 so that the photoconductive surface 11 faces the projector 20 in a position to be exposed by a light image.

Means are provided to hold the recording medium -12 in a stationary position during the entire process in which a colored print is formed on the photoconductive surface 11. To this end, the upper surface 63 of the platen 62 is formed with a rectangular groove 82, as shown in FIGS. 1 and 4. The groove 82 communicates with a conduit 84 in the platen 62, and the conduit 84 is connected to a vacuum pump 86 (FIG. 2) through a flexible hose 88. When the vacuum pump 86 is in operation, the recording medium 12 is held firmly in place by the suction created within the groove 82. The recording medium 12 cannot be moved while the vacuum pump 86 is in operation.

The processing head-The photoconductive surface 11 of the recording medium 12 is electrostatically charged uniformly by a processing head 90, and the subsequent electrostatic latent images formed on the photoconductive surface 11, are toned and rinsed by the processing head 90. The processing head 90, shown in FIGS. 1 and 4, is shown in detail in FIGS. 6 and 7. The processing head 90 comprises two separable parts, fluid applicator means 92 and fluid removal means 94. The fluid removal means 94 is a member formed with an elongated slot 95 therethrough, extending from a top surface 96 to a bottom fiat surface 98 of the member, The fluid applicator means 92 comprises mainly a relatively flat rectangular member 99 of insulating material, such as Lucite, disposed Within the slot 95, well spaced from the side walls of the fluid removal means 94 that define the slot 95. A pair of extending tabs 100 and 102 are fixed adjacent to the upper edge of the fluid applicator means 92 and are disposed to rest on the upper surface 96 of the fluid removal means 94, maintaining the fluid applicator means 92 in position to apply a selected toner to the recording medium 12.

A plurality of flexible tubes 104, 106, 108, 110, and

112 communicate with separate openings in the fluid applicator means 92 which openings, in turn, communicate with a metal manifold 114 (FIGS. 7 and 9) disposed along the lower edge of the fluid applicator means 92. Each of the tubes 104, 106, 108, 110, and 112 is connected to a separate one of tanks 104a, 106a, 108a, 110a, and 112a through a separate one of solenoid valves 104b, 106b, 108b, 11011, and 11217, as shown in FIGS. 1 and 2. The manifold 114 is formed with an elongated slit 115 through which selected liquids can flow onto the surface 11 of the recording medium 12, when programmed to do so by the control circuit. The metal manifold 114 is electrically insulated from the apparatus by the rectangular member 99 of insulating material so that the manifold 114 may be biased with a suitable voltage to function as a developing electrode, if desired, in a manner well known in the art.

The lower surface 98 of the fluid removal means 94 is formed with a recess 116 spaced from the Walls that define the slot 95. A conduit 118 in the fluid removal means 94 communicates with the recess 116, adjacent one end of the conduit 118, and with a flexible hose 122, adjacent the other end of the conduit 118. The hose 122 is connected to a vacuum pump 124 (FIG. 2) for creating a strong vacuum within the recess 116 for the purpose hereinafter appearing. A vacuum gauge 117 (FIG. 1) is connected to the vacuum system to indicate the degree of vacuum produced, usually in a range of inches to 24 inches of water.

The bottom surface 98 of the fluid removal means 94 is also formed with a recess 125, parallel to the recess 116, for disposing a thin corona discharge wire 126 therein. The wire 126 is electrically insulated from the fluid removal means 94 by a pair of insulators 128 and 130, and the wire 126 is electrically connected to a high voltage (about 9 kv. steady, or a pulsed, about 5,000 Hz, Voltage of about 6 kv.) power supply 132 through a conductor 134. At appropriate times, determined by the control circuit, the (DC or pulsed DC) voltage of suflicient amplitude is supplied between the wire 126 and the metal platen 62 to produce a corona discharge of desired polarity around the wire 126, whereby to charge the photoconductive surface 11 of the recording medium 12 in a manner to be hereinafter explained. If the photo-conductive surface 11 is zinc oxide, for example, the voltage applied to the wire 126 is about 9,000 volts DC with respect to the platen 62 to charge the photoconductive surface 11 negatively.

The processing head 90 is adapted to be reciprocated over, and slightly spaced from, the photoconductive surface 11 of the recording medium 12 so that, in one direction of motion, an electrostatic latent image can be toned with an appropriate toner and, in the opposite direction of motion, the toned image can be rinsed and the photoconductive surface 11 can be electrostatically charged in preparation for the formation of subsequent electrostatic latent images. To this end, the head 90 has two plates 136 and 138 (FIGS. 6 and 7) adjustably fixed to the opposite ends of fluid removal means 94. The plate 136 has an ear 140 (FIGS. 7 and 8) extending perpendicularly therefrom. The ear 140 is formed with a hole 141 for receiving therein a pin 142 of a carriage 144. Similarly ,the plate 138 has an ear 146 extending perpendicularly therefrom. The ear 146 is formed with a hole 147 for receiving therein a pin 148 of the carriage 144.

The carriage 144 is adapted to move the processing head 90 in a reciprocal motion and comprises a plate 150 disposed below the platen 62, as shown in FIGS. 4, 8, and 9. An internally-threaded nut 152 is fixed beneath the plate 150 so as to engage a lead screw 154 threadably therein. One end of the lead screw 154 is journaled in a vertical bracket 156 (FIG. 4) that supports one end of the platen 62. The other end of the lead screw 154 is coupled through a suitable gear train 155 to a reversible motor 160 which, in turn, is controlled by a commercially available reversible motor control apparatus 162 and a timer T1, shown in FIG. 1. The motor 160 is controlled by the control circuit, to be explained hereinafter in detail, to rotate in either of two opposite directions, whereby to move the processing head over the photoconductive surface 11 of the recording medium 12 in one direction to apply toner to an electrostatic latent image on the photoconductive surface 11 and in the reverse direction to rinse the toned image and to simultaneously charge the photoconductive surface 11 for the formation thereon a subsequent electrostatic latent image.

Means are provided to charge only the exact image area of the photoconductive surface 11 electrostatically so as to leave a white border around the finished colored electrophotographic print. To this end, a cam operated switch 163 (FIG. 1, and FIG. 4 in phantom) is fixed to one side of the carriage 144 so that it cooperates with a fixed cam 164, fixed to the bed 65, to energize the corona discharge wire 126 for a predetermined time only. Thus, a white border can be produced at opposite ends of the finished colored print. A white border can also be produced on the opposite sides of the print by limiting the Width of the groove 125, as by insulating material 127 (FIG. 7) on opposite ends of the groove 125, thereby confining the corona discharge from the Wire 126 to a predetermined width.

The carriage 144 has guide wheels 166, 167, 168, and 169 (FIG. 8) that engage the side walls of the platen 62 to guide the carriage 144 in its reciprocal movement. The processing head 90 is removably attached to the carriage 144 by inserting the head 90 so that the pins 142 and 148 of the carriage 144 extend through the holes -141 and 147 of the ears and 146, respectively, of the head 90. Guide wheels 170 and 172, fixed to the plate 136, and guide wheels 174 and 176, fixed to the plate 138 ride on the surface 63 of the platen 62 and serve to guide the head 90 over the recording medium 12 and to maintain the bottom surface 98 of the head 90 a predetermined distance (about 0.015 inch from the photoconductive surface 11 of the recording medium 12.

Referring now to FIGS. 10 and 11 of the drawings, there is shown another embodiment 90a of processing head. The processing head 90a is substantially similar to the processing head 90 in operation, but the processing head 90a is preferred for processing relatively large surface areas because it provides a very even distribution of suction. The processing head 90a differs from the processing head 90 in that the processing head 90a has two parallel channels 116a and 116bformed in the bottom surface 98 of the fluid removal means 94. The grooves 116a and 116b are separated from each other, but they substantially surround, and are spaced from, the slot 95. A conduit 118a in the fluid removal means 94 has one end communicating with the groove 116a and an opposite end communicating with a flexible hose 122a. A conduit 118b in the fluid removal means 94 has one end communicating With the slot 11617 and another end communicating with a flexible hose 1221), as shown in FIGS. 10 and 11. The hoses 112m and 12% are connected to each other through a T-coupling 1220 which, in turn, is adapted to be connected to the vacuum pump 124 through a flexible hose, such as the hose 122.

The vacuum pump 124 may be one operated directly by an electric motor. A fire-proof vacuum pump 124, as shown in FIG. 2, may be desired in some apparatus 10, and is one operated on the venturi principle wherein a stream of air is applied to an inlet and removed from an outlet 173 of the pump 124. The venturi-type vacuum pump is preferred when volatile, easily combustible liquids are used in the apparatus 10.

In operation, the processing head 90 (or 90a) applies a selected liquid (toner or rinse) to the photoconductive surface 11 through its fluid applicator means 92. The appropriate liquid is fed to the slotted manifold 114 through selected conduits and tubes by solenoid valves controlled by the control circuit, in a manner to be hereinafter explained.

The appropriate liquid is applied to the photoconductive surface 11 as the processing head 90 moves over, and slightly spaced from, the photoconductive surface 11. All excess liquid is removed from the photoconductive surface 11 by the suction provided within the grooves 116 in the processing head 90 (and the grooves 116a and 116]) in the processing head 90a). Ambient air, available through the slot 95 and from periphery of the processing head 90, is sucked into the aforementioned grooves by the suction produced therein and entrains any excess liquid applied to the photoconductive surface 11, leaving the photoconductive surface 11 substantially dry.

The liquid toners comprise a suspension of pigmented particles in an electrically insulating carrier liquid to which a small amount of an electrostatic control agent has been added. The control agent is usually a soluble resin, such as Pliolite D, a styrene/butadiene (Goodyear Tire & Rubber Co.). A preferred rinse liquid is a highly volatile, relatively high flash point fluid such as Freon TF (trichlorotrifiuoro ethane). This liquid evaporates almost instantly when applied to the photoconductive surface 11. Hence, a previously developed image, that is, an electrostatic latent image on the photoconductive surface 11 to which a suitable colored toner I has been applied from the processing head 90, is rinsed to remove any excess toner and to substantially fix the toned image. The fixing of the toned image results from the rapid evaporation of the rinse liquid, leaving the resinous electrostatic control agent from the toner to form a very thin protective coating over the toned image. The rinse liquid may also slightly soften the photoconductive coating temporarily and thereby aid in the fixing process of each toned image.

When a colored electrostatic print on a recording medium 12 is completed by the apparatus 10, the vacuum produced within the groove 82 in the platen 62 is removed, and the recording medium 12 is moved out of the apparatus in the direction indicated by the arrow 180 in FIG. 1. The latter operations are controlled, in part, by a timer T-6 fixed to the rear of the rear wall 44. The timer T6 cuts off the vacuum pump 86, controls the duration of the movement of the recording medium 12, and then shuts off the apparatus 10, in accordance with the program of the control circuit (FIG. 13).

OPERATION OF THE AUTOMATIC ELECTRO- PHOTOGRAPHIC APPARATUS The operation of the apparatus 10 for making a colored electrophotographic print on the photoconductive surface 11 of the recording medium 12 from an original colored transparency will be explained with the aid of the timing diagram of FIG. 12 and the schematic wiring diagram of FIG. 13. In FIG. 12, each of the time units shown is about thirty seconds in duration. The duration of each of these time units, however, is an arbitrary period of time and may be varied by varying one or more of the components of the apparatus 10. For example, by increasing the intensity of the light from the projector 20, the exposure time for each light image may be decreased.

In FIG. 13, the schematic symbols have the same reference characters as the components they represent in the other figures of the drawings. Most of the components of the control circuit in FIG. 13, as previously described, are within the compartment 42 attached to the rear wall 44 of the cabinet 13. A shaft of a motor M2 in the control circuit is connected to 12 cams C1C12 to rotate them simultaneously. Each of the cams C1-C12 is adapted to actuate a separate switch at an appropriate time during one revolution of the shaft of the motor M2. All of the switches in the control circuit are illustrated in their normally-opened or normally-closed positions when the control circuit is not energized. Each of the seven timers T1-T7 has a separate relay switch connected to it that is adapted to be activated for the time period for which the timer is preset. Thus, the timer T1 has one relay switch R4 associated with it. Timers T2-T5 and T7 have relay switches R6, R7, R8, R9, and R18, respectively, associated with them, and each of these relay switches functions, when energized, to turn on an exposure lamp 20w (FIG. 13) in the projector 20 and to stop the cam motor M2 for the time period preset by its associated timer. The timer' T6 has a relay switch R15 associated with it and serves to perform shutting down operations of the apparatus after the colored electrophotographic print has been completed.

Two stepping switches S2 and S3 are associated with the cams C3, C4, and C5 to control the exposure times of the different colored light images projected onto the photoconductive surface 11 of the recording medium 12 and to apply a different one of four toners to each of the latent electrostatic images formed on the photoconductive surface 11.

A source of AC volts) power is applied to a pair of electrical conductors 200 and 202 by closing a double pole switch 204 and momentarily closing a springbiased starter switch 206 (or 26). The starter switch 206 may be used for test purposes. A hold-down relay 208 is now actuated, applying the source of AC voltage to the conductors 200 and 202. By momentarily closing the starter switch 206 (or 26), the cam motor M2 is started, the recording medium, hold-down vacuum pump 86 is energized, the vacuum pump 124, if electric, is energized, and power is applied to all switches, which, when closed, supply current to the components connected in series with them, as will be hereinafter explained. The starter switch 26 is associated with the slide holder 18 of the projector 20 so that it can be momentarily actuated automatically when the color transparency 17 to be copied is inserted into the projector 20, as explained previously.

In making a colored electrophotographic print from the colored photographic transparency 17, inserted in the projector 20, the cams C1C12 operate through five cycles of revolution. In the first cycle of revolution of the cams C1C12, the light transmission, that is, the photographic density of the photographic transparency 17 is measured (tested) by the photoelectric cell 60, and the lens opening, that is, the diaphragm setting, of the projector 20 is adjusted, in a manner to be explained hereinafter in detail. During this first cycle of revolution, the photoconductive surface 11 of the recording medium 12 is also rinsed, to clean it, and charged electrostatically to prepare it for the production of the first latent electrostatic image. In the next four cycles of revolution of the cams C1C12, four colored images, black, cyan, magenta, and yellow are superimposed over each other on the photoconductive surface 11 to provide the colored electrophotographic print whose resultant colors are substantially the same as those of the original colored transparency 17.

Exposure Test (first cycle of rotation of cams C1- C12).The colored photographic transparency 17 to be copied is inserted into the slide holder 18 of the enlarger 20, and the slide holder 18 is rotated so that its cam 24 actuates the starter switch 26 momentarily as the transparency 17 is fixed in place within the projector. The cam motor M2 is now energized, rotating the cams C1C12. First, cam C4 closes its associated switch and applies current to the stepping switches S2 and S3, stepping the armatures of these switches from Y contacts (where they had been left after a previous colored electrophotographic print had been made) to EX contacts. Next, cam C1 closes its associated switch and energizes the filter solenoid 46. This action raises the solenoid pin 48 from one of the dimples 50. Cam C2 now closes its associated switch and energizes the filter motor M3, causing the filter wheel 36 to rotate. The filter wheel 36 stops rotating when the solenoid pin 48 is engaged by a '9 dimple 50, thereby aligning the exposure test filter beneath the lens 39 of the projector 20.

The exposure test filter may be of any color, clear, or even entirely absent, depending upon the sensitivity and color response of the photoelectric cell 60 which is to detect the transmission of light through the photographic transparency 17. Next, cam 3 closes its associated switch and energizes a relay switch R17 which, in turn, actuates the exposure time T7. The timer T7 now energizes its associated relay switch R18 to stop the cam motor M2 and to turn on the light 20a in the enlarger 20, thereby exposing the photoelectric cell 60 with light transmitted through the transparency 17. The time of exposure provided by the timer T7 is preset to allow the photoelectric cell 60 to provide the exposure control apparatu 52 with a signal whose amplitude energizes the motor 54 in a direction to adjust the lens opening of the projector 20, in a manner known in the art.

The cam C5, which is the next to operate, is used to energize toner solenoid valves. Since no toner is applied to the recording medium 12 during the exposure test cycle, the toner solenoid valves are not actuated in the first cycle of rotation of the cams. Thus, no connections are made to the EX contact of the stepping switch S3.

The next cam to operate is the cam C6. The cam C6 closes its associated switch, sending current through a relay switch R1 which energizes the drive motor control apparatus 162 and causes the motor 160 to move the processing head 90 to the left. The cam 7 operates its associated switch simultaneously with the operation of the cam 6 and energizes the process timer T1 for a preset time. The relay switch R4 is energized by the process timer T1 to cut off power to the cam motor M2, stopping the latter for the period of the preset time of the timer T1, the time necessary for the processing head 90 to move to the left across the photoconductive surface 11 of the recording medium 12.

Initial rinse and electrostatic charge of the photoconductive surface (during the first cycle of revolution of the cams C1C12).-The cams C8 and C9 are the next to operate their associated switches. Cam C9 energizes the process timer T1 which, in turn, turns off the cam motor M2 by energizing the relay switch R4. During the preset time of the process timer T1, the came C8 energizes the relay switches R2 and R3. Energizing the relay switch R2 causes the drive motor control apparatus 162 to reverse the direction of rotation of the motor 160, causing the processing head 90 now to move to the right across the photoconductive surface 11 of the recording medium 12. While the processing head 90 is so moved, the energized switch R3 sends current to a rinse solenoid valve S4 which, in turn, allow a rinse solution to flow thruogh the processing head 90. Energizing the relay switch R3 also closes the switch between the charger power supply 132 and the corona discharge wire 126 in the processing head 90. The wire 126 will discharge a corona only while the switch 163 is actuated by the cam 164 to provide a border for the finished electrophotographic print. Thus, the photoconductive surface 11 is simultaneously both rinsed and charged while the processing head 90 moves to the right. The processing head 90 stops moving to the right after the period of time for which the process timer T1 was preset.

The rinsing solution, such as Freon TF (trichlorotrifiuoro ethane) or Freon MP (trichloromonofluoro methane), is very volatile and is evaporated almost as fast as it is applied to the photoconductive surface 11. This initial rinsing cleans the photoconductive surface 11 and prepares it to accept a good electrostatic charge. It 'has been observed that the uniformity and intensity of the electrostatic charge accepted by the photoconductive surface 11 is better after the surface has been rinsed than it would be without the rinsing operation. Dimethylpolysiloxane, having a viscosity of about 0.5 centistokes, may also be used as a rinse liquid.

The cams C10, C11, and C12 actuate their associated switches during the first cycle of rotation, but they do not operate any equipment at this time because the cutoff timer T6 is not actuated. The cutoff timer T6 is actuated only during the last image toning (developing) operation.

Production of the black image (second cycle of revolution of the cams C1-C12.--The first cam to close its associated switch in the second cycle of revolution of the cams is cam C4. This action energizes the stepping relay switches S2 and S3, moving the armatures of these switches to the BL contacts. Cams C1 and C2 now close their associated switches, energizing the solenoid 46, turning the filter wheel to the next filter position, and disposing an orange filter (No. B) beneath the lens 39 of the projector 20. The cam C3 actuates its associated switch and energizes the relay switch R14 which, in turn, energizes the black timer T5 for a preset period. The black timer T5 now energizes its associated relay switch R9 which simultaneously stops the cam motor M2 and energizes the exposure lamp 20w of the projector 20 for the period of time preset on the timer T 5. The light image projected through the filter (No. 85B) onto the previously charged photoconductive surface 11 forms a latent electrostatic image on the photoconductive surface 11 which image will be toned with a black toner.

The cam C5 now actuates its associated switch to provide current to the black toner solenoid valve, causing liquid black toner to flow to the processing head The cam C6 actuates its associated switch simultaneously with the actuation of the switch associated with the cam C5, energizing the relay switch R1 which, in turn, energizes the drive motor control apparatus 162 and causes the motor to move the processing head 90 to the left. During this action the processing head 90 applies the liquid black toner to, and sucks up excess toner from, the photoconductive surface 11, whereby to tone the electrostatic image black. The cam C7 actuates its associated switch simultaneously with the actuation of the switch associated with cam C6 to turn on the process timer T1 for a preset time. During this time the relay R4 stops the cam motor M2 so that the liquid black toner can be applied to the photoconductive surface 11. After the electrostatic latent image has been toned with the black toner, the cams C8 and C9 actuate their respective switches. The cam C8 energizes the relay switches R2 and R3 to reverse the direction of movement of the processing head 90, to energize (open) the rinse solenoid valve S4, and to connect the charger power supply 132 to the wire 126. Thus, the liquid rinse and the electrostatic charge are applied substantially simultaneously to the photoconductive surface 11 to prepare the surface for the next latent electrostatic image, as the processing head 90 moves to the right. The cam C9 stops the cam motor M2 through the process timer T1 and its associated relay switch R4 during the movement of the processing head 90 to the right.

The cams C10-C12 do not operate any components during this cycle of revolution because the cutoff timer T6 is not energized at this time.

Production of the cyan and magenta images (third and fourth cycles of revolution in the cams).-A separate latent electrostatic image is produced, toned, and rinsed during each of the next two cycles of revolution of the cams C1-C12 in substantially the same manner described for the production, toning, and rinsing of the black image.

For the production of the cyan toned image (in the third cycle), the armatures of the stepping switches S2 and S3 are stepped to the C contact positions, and the charged photoconductive surface 11 is exposed through a red filter (No. A25) for a preset period of the cyan timer T4.

For the production of the magenta toned image (in the fourth cycle), the armatures of the stepping relays S2 and S3 are stepped to the M contact positions, and the charged photoconductive surface 11 is exposed with a light image through a green filter (No. B58) for a preset period of the magenta timer T3. After each of the third and fourth cycles of revolution of the cams C1-C12, the photoconductive surface 11 is left rinsed and electrostatically charged in readiness for the production of a subsequent, latent electrostatic image.

Production of the yellow image (fifth cycle of revolution of the cam C1-C12).The operation of the last cycle of the revolution of the cams C1-C12 differs somewhat from the preceding three cycles in that the last (fifth) cycle of revolution of the cams C1C12 includes shutdown operations after the toning of the yellow image.

As in every cycle of revolution, the cam C4 actuates its associated switch first. In the fifth cycle, this action energizes the stepping relays S2 and S3 and causes their armatures to step to the Y contact positions. Next, cams C1 and C2 operate simultaneously, lifting the solenoid pin 48 from a dimple 50 and allowing the filter wheel 36 to rotate and bring a blue filter (No. 47B) into position.

The cam C3 now actuates its associated switch, energizing the relay switch R11 which stops the cam motor M2 and turns on the lamp 20a in the projector 20, via relay switch R6, for a period of preset time on the timer T2. Thus, the previously charged photoconductive surface 11 is exposed to a light image through the blue filter to provide a latent electrostatic image that is to be toned with a yellow toner. Next, the cams C5-C7 operate simultaneously to actuate their associated switches. The cam C5 energizes the yellow solenoid valve, permitting liquid yellow toner to flow to the processing head 90. The cam C6 energizes the relay switch R1 which, in turn, actuates the drive motor control apparatus 162 and the motor 160 to move the processing head 90 to the left. The cam C7 actuates the process timer T1 which, in turn, energizes the relay switch R4 for a period of time preset on the process timer T1 to stop the cam motor M2 while the processing head 90 is moving to the left. Next, the cam C8 closes its associated switch and energizes the relay switch R2 to reverse the motor 160 through the motor control apparatus 162 and cause the processing head 90 to move to the right. The cam C8 also energizes the relay switch R3 which, in turn, energizes the rinse solenoid valve S4, allowing liquid rinse to flow to the processing head 90 to rinse the yellow toned image. The charger power supply 132 does not energize the corona discharge wire 126 at this time because the cutoff timer T6 has been energized by the cam C5, via the Y contact position of the stepping relay S3 and a relay switch R16 (when the yellow solenoid valve was opened). The cam C9 now closes its associated switch to energize the process timer T1 for a period of time, the duration of time the processing head 90 moves to the right.

With the cutoff timer T6 actuating the relay switch R15, the cam 10, by actuating its associated switch, can now energize the relay switch R10 to de-energize the vacuum pumps 86 and 124, removing the vacuum that holds the recording medium 12 in place on the platen 62. The relay switch R10 also enables the switch actuated by the cam C11 to energize the drive motor 78 to drive the rollers 70 and 72 and to move the recording medium 12, with the finished colored electrophotographic print on it in the direction of the arrow 180, out of the apparatus 10.

The relay switch R15 associated with the cutoff timer T6 also disconnects the charger power supply 132 from the corona discharge wire 126 during the last rinse (the rinse of the yellow toned image). This action prevents the finished colored electrophotographic print from picking up dust. With the cutoff timer T6 still in operation, its associated relay switch R15 opens a normally-closed switch that normally shorts the starter switches 206 and 26 so that the cam C12 can now actuate its associated switch and de-energize the hold-down relay 208, whereby to disconnect the power (115 volts AC) from the conductors 200 and 202 and to shut down the apparatus 10.

Thus, there has been described improved automatic apparatus for making a colored electrophotographic print from an original colored image. Although the original colored image has been described as a colored transparency, it may be a colored photographic print or even a plurality of colored separation transparencies. If colored separation transparencies are used, the colored filters of the apparatus are not necessary.

In the embodiment of the improved automatic apparatus described, a colored electrophotographic print having substantially the same natural colors as the original colored transparency is produced. The improved automatic apparatus, however, may be used to make colored electrostatic prints whose colors may differ in any desired manner from those of a colored original. Although a plurality of latent electrostatic images have been toned with different toners in a certain sequence, the colored toners may be applied in a different sequence without departing from the spirit of the invention. In fact, the improved automatic apparatus may also be used advantageously for making electrophotographic prints in black and white only.

An important feature of the present invention is the arrangement of the apparatus by means of which the recording medium is held stationary with respect to the light image projector during its entire processing 50 that the plurality of toned images can be produced in perfect registration. Thus, the possibility of misregistration is practically avoided.

Another important feature of the improved apparatus is preferably the provision therein for a rinsing operation by means of which the photoconductive surface is initially cleaned and prepared to accept an adequate electrostatic charge. The rinsing operation to accept an adequate electrostatic charge. The rinsing operation also removes excess toner from the toned images and provides a finished print wherein the relatively thin layers of superimposed toned images can blend together to provide substantially the true colors of the colored original image. The rinsing liquid also serves to substantially fix the toned images, as well as the finished electrostatic print, so that the latter may be subsequently handled without smearing.

It is also within the contemplation of the present invention to provide the composite electrophotographic print with a final protective coating, such as a 1% solution, by weight, of isobutyl methacrylate polymer in trichlorotrifluoro ethane, applied through the processing head, if so desired.

I claim:

1. In apparatus for making an electrophotographic print on a photoconductive surface of a recording medium from an original image, wherein said photoconductive surface is electrostatically charged, exposed to a light image of said original image to form an electrostatic latent image, and said latent image is toned, the improvement comprising:

means to hold said recording medium stationary until said electrophotographic print is made,

a processing head comprising electrostatic charging means, fluid applicator means, and fluid removal means,

means to reciprocate said head over, and at a fixed distance from said photoconductive surface,

means to energize said charging means, to apply a rinse liquid to said fluid applicator means, and to remove excess rinse liquid through said fluid removal means during the movement of said head in one direction of reciprocation, whereby to charge and to clean said photoconductive surface, and

means to apply toner to said fluid applicator means, to develop said latent image, and to apply suction to said fluid removal means to remove excess toner from said photoconductive surface during the movement of said head in an opposite direction to said one direction of reciprocation.

2. In apparatus for making an electrophotographic print as defined in claim 1, said means to hold said recording medium stationary comprises:

a platen,

a groove formed in said platen adjacent to said recording medium, and

means to apply suction to said groove, whereby to hold said recording medium stationary during the making of said electrophotographic print.

3. In apparatus for making an electrophotographic print as defined in claim 1,

said fluid applicator means is removably attached to said fluid removal means, whereby said fluid applicator means may be easily cleaned, and

said charging means is integral with said fluid removal means, whereby said photoconductive surface can be both rinsed, to clean it, and prepared, to receive said electrostatic charge, substantially simultaneously as said head is moved in said one direction.

4. In apparatus for making an electrophotographic print as defined in claim 1, said means to reciprocate said head over, and at a fixed distance from, said photoconductive surface comprises:

a platen,

a carriage disposed beneath said platen,

screw means including a screw and a nut cooperatively associated with said carriage to reciprocate the movement of said carriage in accordance with the direction of rotation of said screw,

guide wheels,

means fixing said guide wheels to opposite sides of said head, and

means removably attaching said head to said carriage so that said guide wheels engage said platen, whereby to space and to guide said head a predetermined distance from said platen as said head is reciprocated.

5. In apparatus for making an electrophotograp'hic print as defined in claim 1, said means to energize said charging means comprises switching means cooperatively associated with the movement of said head to energize said charging means on said head only while said head is moving over a predetermined portion of said photoconductive surface, whereby to provide said electrophotographic print with a border free from said toner.

6. In automatic apparatus for making an electrophotographic print on a photoconductive surface of a recording medium from an original image, wherein each of a plurality of different electrostatic latent images on said photoconductive surface is produced by projecting a light image of said original image through a dilferent one of a plurality of light absorption media, and wherein each of said latent images is toned with a different one of a plurality of toners, and the toned images are superimposed on each other, in registration, to provide said colored electrophotographic print, the improvement comprising:

means to hold said recording medium stationary at a predetermined distance from said original image until said electrophotographic print is made,

a processing head comprising electrostatic charging means, fluid applicator means, and fluid removal means,

means to reciprocate said head over, and slightly spaced from, said photoconductive surface,

means to energize said charging means, to apply a rinse solution to said fluid applicator means, and to apply suction to said fluid removal means during the movement of said head in one direction of its reciprocal movement, and

means to apply a diiferent one of said plurality of toners to said fluid applicator means to develop a different one of said latent images, respectively, and to apply suction to said fluid removal means to remove excess toner from said photoconductive surface during the movement of said head in an opposite direction, to said one direction, of said reciprocal movement.

7. In automatic apparatus for making an electrophotographic print as defined in claim 6,

said plurality of light absorption media comprises a plurality of light filters,

a projector disposed to project a light image of said original image onto said photoconductive surface, and

means to dispose a different one of said light filters in the path of said projected light image to form one of said different latent images each time said photoconductive surface is electrostatically charged, whereby each of said different latent images can be toned with a different one of said toners to provide said electrophotographic print.

8. In automatic apparatus for making an electrophotographic print as defined in claim 6, said means to hold said recording medium stationary comprises:

a platen for supporting said recording medium,

a groove formed in said platen beneath said recording medium, and

means to apply suction in said groove, whereby to hold said record stationary during the making of said electrophotographic print.

9. In automatic apparatus for making an electrophotographic print as defined in claim 6,

said electrostatic charging means and said fluid removal means form an integral unit, and

said fluid applicator means is removably attached to said integral unit, whereby said fluid applicator means may be easily cleaned, and said photoconductive surface can be both rinsed, and charged substantially simultaneously.

10. In automatic apparatus for making an electrophotographic print as defined in claim 6, said means to energize said charging means in said head comprised cammed switching means cooperatively associated with the movement of said head to energize said charging means only during a predetermined distance along the path of travel of said head in said one direction over said photoconductive sheet, whereby to provide said electrophotographic print with a border free from said toners.

11. In automatic apparatus for making an electrophotographic print as defined in claim 6,

a light projector, to project said light image,

means to sense the intensity of said light image projected by said projector, and

means responsive to the intensity of light sensed by sensing means coupled to said projector to regulate the light from said projector to a predetermined in tensity,

means to reciprocate said head through a plurality of cycles, each of said cycles comprising the movement of said head in both said one and said opposite directions, and

means to prevent the application of toner to said fluid applicator means during the movement of said head in said opposite direction of the first of said cycles, and to sense the intensity of said light image and to regulate said light from said projector, and

means to apply said rinse solution to said fluid applicator means and suction to said fluid removal means during the movement of said head in said one direction of said first cycle.

12. In apparatus for making an electrophotographic print on a photoconductive surface of a recording medium from an original image, the combination of:

means to position said recording medium and said original image in a fixed spaced-apart relationship with each other until said electrophotographic print is made,

a processing head comprising electrostatic charging means, fluid applicator means, and fluid removal means,

control means to reciprocate said head over, and at a fixed distance from, said photoconductive surface,

control means to apply an electrostatic charge to said charging means during the movement of said head in one direction of reciprocation, whereby to charge said photoconductive surface,

control means to stop said head and to project a light image of said original image onto said charge photoconductive surface to form an electrostatic latent image thereon, and

control means to move said head in an opposite direction, to said one direction, and to apply liquid toner to said fluid applicator means to develop said latent image, and to apply suction to said fluid removal means to remove excess liquid toner from said photoconductive surface.

13. In apparatus for making an electrophotographic print as defined in claim 12,

said liquid toner comprises a resin,

a volatile rinse liquid in which said resin is soluble, and

control means to move said head again in said one direction and to apply said volatile liquid to said fluid applicator means and to apply suction to said fluid removal means to remove and to evaporate said volatile liquid, whereby to leave a coating of said resin on said toned image to substantially fix said toned image to said photoconductive surface.

14. In apparatus for making a colored electrophotographic print on a photoconductive surface of a recording medium from a colored original image, the combination of:

means to position said photoconductive surface a predetermined distance from said original image until said electrophotographic print is made,

a plurality of different filters,

a processing head comprising electrostatic charging means, fluid applicator means, and fluid removal means,

a control circuit including means to reciprocate said head over, and slightly spaced from, said photoconductive surface,

means including said control circuit to apply a rinse liquid to said fluid applicator means, to apply suction to said fluid removal means to remove excess rinse liquid, and to energize said charging means during the movement of said head in one direction of reciprocation, whereby to clean and to electrostatically charge said photoconductive surface,

means including said control circuit to expose said charged photoconductive surface with a light image of said original image through a selected one of said filters, whereby to form an electrostatic latent image on said charged photoconductive surface, and

means including said control circuit to apply a selected one of a plurality of toners to said flui-d applicator means to tone said latent image, and to apply suction to said fluid removal means to remove excess toner during the movement of said head in an opposite direction, to said one direction, over said photoconductive surface,

15. In apparatus for making a colored electrophotographic print as defined in claim 14,

means including said control circuit to reciprocate said head through a plurality of cycles, each of said cycles comprising the movement of said head in both said one and said opposite directions.

means including said control circuit to prevent the application of a toner to said fluid applicator means during the movement of said head in said opposite direction of the first of said cycles,

means to sense the intensity of said exposure means,

and to regulate it to a desired intensity, and

means to apply said rinse liquid to said fluid applicator means, to apply suction to said fluid removal means, and to energize said charging means during the movement of said head in said one direction of said first cycle.

16. In apparatus for making a colored electrophotographic print as defined in claim 15,

means including said control circuit to expose said charged photoconductive surface with a light image of said original image through a different one of said filters to form a different electrostatic latent image before the beginning of cycles subsequent to said first cycle,

means including said control circuit to tone each of said different latent images with a different toner during the movement of said head in said opposite direction in said subsequent cycles, and

means to apply said rinse liquid to said liquid applicator means and suction to said fluid removal means, and to energize said charging means during the movement of said head in said one direction of said subsequent cycles, whereby to tone and to rinse said latent images and to charge said photoconductiv surface for each subsequent exposure.

17. In apparatus for making a colored electrophoto graphic print as defined in claim 16,

each of said toners comprises either black, magenta, cyan, or yellow pigments, a control agent, and an insulating carrier liquid,

said rinse liquid comprises either trichlorotrifluoro ethane, trichloromonofluoro methane or dimethylpolysiloxane, and

said filters comprise red, green, blue and orange filters.

18. In apparatus for making an electrophotographic print on a recording medium wherein said recording medium is electrostatically charged, exposed to a light image, and toned, the improvement comprising:

means for holding said recording medium in a predetermined position,

exposure means for projecting a light image of a subject to be copied onto said recording medium in said predetermined position,

a processing head adapted to be moved across the surface of said recording medium a plurality of passes when said recording medium is in said predetermined position, said head comprising corona discharge means for electrostatically charging said recording medium when said head is moved thereacross,

fluid applicator means for applying a fluid to said recording medium when said head is moved thereacross, and

fluid removal means for removing excess fluid from said recording medium when said head is moved thereacross,

suction means,

means for holding rinse liquid,

means for holding toner liquid, and

control means for energizing said corona discharge means, for energizing said exposure means, for feeding said rinse liquid to said fluid applicator means, for feeding said liquid toner to said fluid applicator means, and for applying said suction means to said liquid removal means during selected ones of said passes of said head, whereby to charge, to expose, to tone, to rinse, and to dry said recording medium.

19. In apparatus for making an electrophotographic print as described in claim 18,

said head is reciprocated over, and slightly spaced from, said recording medium a plurality of cycles of reciprocation, and

said control means comprises means to feed said toner liquid to said fluid applicator means during at least a portion of the time said head as moving in one direction of one of said cycles of reciprocation, to energize said corona discharge means to to feed said rinse liquid to said fluid applicator means during at print on a photoconductive surface of a recording medium wherein said recording medium is electrostatically charged, exposed to a light image to form an electrostatic latent image, and the latent image is toned, the improvement comprising:

means for holding said recording medium in a predetermined position,

exposure means for projecting a light image of a subject to be copied onto said recording medium when said recording medium is in said predetermined position,

a processing head adapted to be moved across said photoconductive surface of said recording medium a plurality of cycles of reciprocation when said recording medium is in said predetermined position, said head comprising fluid applicator means for applying a fluid to said recording medium when said head is moved thereacross, and

fluid removal means for removing excess fluid from said recording medium when said head is moved thereacross,

suction means,

means for holding rinse liquid,

means for holding toner liquid, and

control means for energizing said exposure means to expose said charged photoconductive surface and to form said latent image, for feeding said toner liquid to said fluid applicator means to develop said latent image, for feeding said rinse liquid to said fluid applicator means to rinse said developed image, and for applying said suction means to said liquid removal means to dry said photoc'onductive surface during selected periods of time in said cycles of reciprocation of said head.

References Cited UNITED STATES PATENTS 2,986,466 4/ 1961 Kaprelian 951.7 3,342,164 9/ 1967 Lewis 118410 3,357,326 12/ 1967 Hunstiger 951.7 3,371,651 3/ 1968 Johnson et a1.

JOHN M. HORAN, Primary Examiner D. B. WEBSTER, Assistant Examiner U.S. Cl. X.R. 

